Apparatus for monitoring the dispensing of liquid



y 27, 1965 1'. H. CORBIN ETAL 3,197,068

APPARATUS FOR MONITORING THE DISPENSING 0F LIQUID Filed April 27, 1964 3 Sheets-Sheet 2 INVENTORS THOMAS H. CORBIN ATTORNEYS m a; E

JOHN E. POULSEN J y 1965 T. H. CORBIN ETAL 7,

APPARATUS FOR MONITORING THE DISPENSING OF LIQUID Filed April 27, 1964 3 Sheets-Sheet 3 m b\b sm m w coo; mm x9 8% m amm m 337. l--

m ow m q 0 m6 5;: m P T XOTI/f X XO 1 vi? YEN SE M \W W Q n H I. OH & 95 x9 4 R No 58 mm :Em tam xmm Nmz }J \mm W ,79 Q; I i ZWII! o we. T mz w in m@ 5m m 252m I: u .w A a moo E09 Em NM xmwm vmv ,w n Bwz VEVW oo In N W V: 39 4d m |i n mm mm! mm mm No w Q a Q) m Ti 1 8 v.9 Bis v6 1 x Q E 2 8 w L 4 k United States Patent 3,197,068 APPARATUS FOR MONITORING THE DISPENSING OF LIQUID Thomas H. Corbin, Palo Alto, and John E. Ponlsen, Santa Clara, Calif, assignors, by mesne assignments, to Corbin-Fernsworth, Inc, Palo Alto, Calif., a corporation of Delaware Filed Apr. 27, 1964, Ser. No. 362,832 13 Claims. (Cl. 222-59) This invention relates to apparatus for controlled feeding and monitoring of drops of liquid or other material delivered in discrete increments. The apparatus is particularly useful in maintaining a closewatch over intravenous feeding of drops of liquid material to humans.

In feeding liquids intravenously to patients it is particularly important in certain circumstances to guard against feeding the patient at a faster rate than intended. In certain instances it is believed that more harm can be done the patient by feeding too rapidly than might be done, for example in an emergency, when all feeding might be terminated.

It is a general object of the present invention to provide an improved scheme for monitoring the feeding of discrete increments of material.

It is another object of the invention to provide a system for insuring against a too rapid feeding of liquid as compared to the selected rate of feeding sought.

It is still another object of the invention to provide a drop feeding system which initiates and accurately controls the number of drops per minute of intravenous liquid delivered to a patient, and which turns itself 01f if the drop rate delivered to the patient is dilferent from the drop rate desired.

It is yet another object to provide a system of the kind described whereby intravenous feeding of liquid is promptly terminated in case of various emergencies, such as power failure, etc., so as to be relatively fail safe.

These and other objects of the invention will be more readily apparent from the following detailed description of a preferred embodiment when considered with the accompanying drawing in which,

FIGURE 1 is a schematic and block diagram of a material feeding and monitoring system according to the invention; and

FIGURES 2 and 3, considered together, provide a schematic circuit diagram of an operating embodiment according to the invention, including values and specifications of circuit components thereof.

In general, the apparatus to be described in detail below includes means serving to feed material by discrete increments thereof for delivery, and means serving to define a selected intended rate of incremental delivery. Means are also provided which serve to sense each increment of material to be delivered and thereby to define the There is also provided means defining a selected drop rate and means serving to sense each delivered drop so as to define the actual drop rate. provided which serve to detect disparity between the actual and selected rates and inactivate the valve means in response thereto in order to arrest further delivery of fluid.

Finally, means are In achieving the foregoing general arrangement, the approach herein has been to employ valve means operable in one condition to pass a drop of the liquid which is to be delivered, and operable in another condition to arrest delivery of the liquid. A first pulse generator is arranged which serves to provide a series of pulses at a selected rate corresponding to the rate of delivery of drops of liquid intended to be achieved. A second pulse generator is arranged to sense each drop of liquid which is delivered. The second pulse generator serves to generate a pulse in response to sensing each drop.

A pair of bi-stable switch means such as conventional flip-flop devices are each coupled to respond to the pulses generated by both the first and second pulse generators. Each bi-stable switch means is, therefore, alternately driven between its two stable states by alternately receiving a pulse respectively from the first and the second pulse generators thereby maintaining an in-phase relationship. However, if this alternating application of pulses to both switching means is interrupted to cause successive application of pulses from either of the pulse generators to the two switching means this change is detected. Means are provided which serve to sense a change in the predetermined phase relationship of the bi-stable devices and to condition the valve so as to terminate delivery of liquid. The existence of a change in the phase relationship of the operation of the two switching means is thereby registered.

Referring in detail to the schematic diagram shown in FIGURE 1 there is provided feeding means 10 serving to feed a series of discrete drops of liquid 11 from a container 12 into the arm of a patient receiving intravenous feeding. Feeding means 10 as schematically shown includes a suitable drop forming outlet 14 disposed to de liver drops from container 12 to a splash chamber 13. An attachable drop sensor assembly includes a light source 15 which directs a beam of light through an aperture 16, and splash chamber 13, to be sensed by a photo responsive device 17. Device 17 serves to generate a signal on line 18 whenever the beam is interrupted by the presence of a drop as at 19. Drops 19 travel along a tube 21 for delivery into the arm of a patient.

Means are provided to control delivery of drops through tube 21. Thus, a valve member 24, operable in one condition to pass a drop of the liquid and operable in another condition to arrest delivery of drops through tube 21 is provided. A solenoid 25 is arranged whereby when it is energized member 24 will be withdrawn against the urging of spring 26. De-energizing solenoid 25 serves to permit spring 26 to cause member 24 to pinch tube 21. Tube 21 is pinched between the free end of member 24 and a fixed portion 27 of the solenoid assembly.

From the foregoing it will be evident that the actual drop rate of liquid being dispensed is sensed by photocell 17. Photocell 17, therefore, serves to function as an impulse generator which provides an impulse corresponding to each drop to be dispensed.

There is also provided another impulse generator which serves to define the desired or selected drop rate for liquid to be fed to a particular patient. Thus, a drop rate generator 31 is provided in the form of a suitable pulse generatorwhich provides a series of output pulses corresponding to the selected drop rate to be established. The frequency of these pulses can vary over a wide range, for example, from 5 to drops per minute or the like and such apulse generator can readily be provided by conventional means, such as by certain relaxation oscillators or the like.

In order to monitor and detect disparity between the actual drop rate and the desired drop rate there is provided a bi-stable switch means such as the main drive flip-flop 32. Flip-flop 32 is of conventional known de- Patented July 27, 1965 3,1 emcee sign; Thus, it will be understood thatfiip-flop 32includes a first input to be applied along line 33 to set the flip-flop and a second input to be applied on line 34 to reset the flip-flop. As is known, a flip-flop has two stable states and these are indicatedby ,the relative voltage level appearing on the twooutput channels 35,36. i A second bi-stable switch means such as the alarm flipflop 37 is arranged similarly to the main drive flip-flop 32 except that there is provided only a single input 38;

Means are provided whereby the drop rate generator 31, serves to dispense a drop of liquid to the patient.

Thus, as a pulse appears at the output line 33 from drop rate generator 31, flip-flop 32 sets output channel 35 in its relatively high level potential. Channel 35, when high, operates a solenoid drivercircuit 45 which feeds a pulse on line 46 to energize solenoid subject to control of an alarm disconnect relay circuit 47. When solenoid 25 is energized, member. 24is withdrawn permitting a drop to be dispensed.

' Th formation of a dropas sensed by photocell 17 providcs a signal which is filtered and amplified by a conventional amplifier unit 49. This sensing signal serves to reset flip-flop 32 by developing a long pulse on input 34.

, The signal from the photo-responsive device 17 is gated via a 150 millisecond monostable one-shot multivibrator 5 1 in order to prevent noise or extra signals from reachingflip-fiop 32 and alarm flip-flop 37 for an elongated period, for example, on the order of 150 milliseconds after the drop occurs, thereby preventing false alarms. Multivibrator 51 can be of any suitable known construction whereby two operating states canbe established. One

state is a stable state while the other is unstable and after being established will revert, after a predetermined period, to the stable state. The output of multivibrator 51 appears simultaneously on lead 34 and on lead 42.

From" the foregoing it will be readily apparent that a predetermined phase relationship is established between the bi-stable state of flip-flop 32 of alarm flip-flop 37. Y

In operation, as drop rate generator 31 provides an inpntpulse simultaneously to both flip-flops 32 and 37, one stable state of each will be established. At the same time a drop will be dispensed. Thereafter, formation of each drop will cause a pulse to be generated whereby flipflop 32 and flip-flop 37 change from their preceding state to their other stable state. So long as the pulse repetition frequency of drop rate generator 31 remains matched with the actual drop formation rate, flip-flop 32 will remain in its predetermined phase relation with respect to flip-flop 37.

However, means are provided to sense a change in the phase relationship and-to cause the valve means to terminate the feeding of liquid Accordingly, a first and second AND gate have been provided, each being coupled to both flip-flops 32, 37.

Flip-flop 32 and flip-flop 37 are each arranged whereby they can operate in-phase with each other. Thus, the high output from flip-flop 32 switches between lines and 36 whereby it appears on line 35 at a time when line 43 is high and neither AND gate receives coincident application of the high states. On theother hand when line 36 is high from the reset pulse to flip-flop 32, line 44 will also be high.

and the bi-stable state The first and second AND gates are designated and shown as a low rate alarm AND gate 52 and as a high rate alarm AND gate 53. Gate 52 is fed by channels 36, 4-3; gate 53 by channels 35,44. The AND gates 52, 53 are of ,a known style whereby coincident application of two relatively high voltage state. signals is required to produce an output signal. It is to be noted that while flipflops 32, 37 are operatively coupled so as to alternate inphase between one stable state and'the other they are coupled out of phase to AND gates 52, 53. Thus, normally only one high voltage state signal will be applied to each of the two AND gates 52, 53.

However, wheneve r both inputs to one or the other of the AND gates 52, '53 are high, then a disparity manifest circuit 54 receives a signal via OR gate 56 from one or the other of gates 52, 53 to provide a signal on line 55. This signal conditions circuit 47 to prevent solenoid 25 from being energized and therebyprecludes further delivery of liquid through tube 21. Circuit 54 is a flip-flop wherebymanual open-circuiting of a control electrode thereof serves to reset the circuit as described below.

Thus, the high outputs from gates 52, 53 are fed to circuit 54 via a conventional OR gate 56 of the type adapted to pass either of two input signals. Assuming that the actual drop rate is low it will be evident that the drop rate generator 31 will provide two successive pulses on outputs 39 and 33 before an actual drop impulse is received by either flip-flop '32 or 37. The output ofdrop rate generator 31 on line 33 will be ineffective to switch flip-flop 32 inasmuch as the latter switches from one state to the other dependent upon the application of pulses a1 ternately to the inputs 33, 34 respectively. On the other hand, flip-flop 37 has but a single input 38 and in response to two successive pulses will change its stable state whereby the high state signal on output channels 43, 44 will switch from one to the other. Thus, the high state signal of one flip-flop is switched whereas on the other, it is not.

In this condition coincident existence of two high voltage signals will occur at AND gate 53.

If theactual drop rate is higher than the desired rate two successive impulses will appear on lines 34, 42 prior to generation of an impulse on lines 39, 33. Successive pulses applied to line 34,'however, will not cause a transfer of the high state from line 35 to line 36' for flip-flop 32, whereas successive pulses on line 42 will cause such a transfer from line 43 to 44. Thus, coincident existence of the high state signals will occur at AND gate 52. Accordingly, in either event circuit 54 is conditioned so as to deactivate the valve means and terminate delivery of liquid. 7

After arresting the feeding of liquid through tube 21, as caused by any rate disparity, the system is reset to re-establish a proper in-phase relation between flip-flops line 63 operatively coupled to actuate a reset circuit 62..

Circuit 62 includes a pair of output leads 64, 65 coupled to respectively reset the alarm flip-flop 37 and the main drive flip-flop 32.

While conventional circuits can be employed in the various boxes referred to above, FIGURES 2 and 3, when taken together provide a preferred operable embodiment of the system when taken with the component values and designationsshown on the drawing. 7

For ease in correlating the system taught in FIGURE 1 to the schematic circuit diagram of FIGURES 2 and 3, phantom lines have been used which somewhat generally enclose the elements thereof in the latter and have been given corresponding reference numerals.

Thus, the amplifier; and filter circuit 49 is comprised of an RC coupled transistor fed from the photoresponsive device 17. The one-shot mono-stable multivibrator 51 includes a pair of transistors of opposite conductivity type whreein the emitter of one includes a pair of diodes poled in a common direction.

Main drive flip-flop 32 includes two transistors wherein the collector of one is fed back to the base electrode of the other. Separate input signals are received to set and reset the device as in the well-known Eccles-Jordan trigger. Thus, flip-flop 32 is diode coupled to receive, and be reset by, pulses or step functions via line 34 defining the actual drop rate. Flip-flop 32 is set by pulses or step functions on line 33 which indicate the desired drop rate developed by pulse generator 31.

Pulse generator 31 includes the unijunction transistor wherein the control electrode is coupled to a junction between a series of three resistors and a relatively large capacitance formedby a pair of parallel condensers which serve to establish the pulse rate when the resistors are varied. V

OR gate 41 includes a conventional arrangement of the two diodes shown wherein a signal on either line 39 or 42 will be fed out on line 38 from the junction between the diodes. The alarm flip-flop 37 is a conventional complernentary flip-flop wherein a single input receives a succession of signals. Each signal received serves to switch the device from one stable state to the other. Thus, since signals are passed to flip-flop 37 via OR gate 41 from either the desired or actual pulse rate generator circuits without ability to distinguish onefrom the other, its state can be compared with the state of flip-flop 32 by means of AND gates 52, 53.

AND gates 52, 53 each include a pair of diodes arranged as is well known.

Circuit 54 provides a flip-flop circuit employing a pair of transistors.- The output from circuit 54, when disparity in the phase relation between flip-flops 32 and 37 has been sensed, serves to de-energize a normally energized relay coil 74 in circuit 47. When the coil 74 is deenergized an armature 71 is spring-transferred to opencircuit the solenoid coil 25 of the valve operating solenoid. At the same time, V1 is applied to lead 63 so as to cause reset circuit 62 to reset both flip-flops 32, 37.

Circuit 62 includes the two diodes poled in a normally non-conducting direction. Transfer of armature 71, however, serves to bias them into conduction to apply a reset function to the base (control) electrodes of one side of each flip-flop 32, 37. Thus, an initial predetermined reset phase relation is established.

Circuit 45 is Zener diode coupled by diode 72 to flipflop 32 and includes a conventional two stage transistor amplifier circuit with the collector of the second stage directly coupled to solenoid coil 25.

A manually operated switch 73, when positioned to the off position serves to de-energize the holding coil 74. Another position of switch 73 serves to permit pulse generator 31 to start dispensing drops while the system becomes adjusted, before implementing the drop arresting control portion of the circuit.

A circuit with the component values and voltages shown was constructed and operated.

Thus, there is provided an improved system for the controlled feeding and monitoring of drops of liquid. Drops are fed by gravity at an accurate rate established by an impulse generator whereby an intended selected rate can be established. It the rate sought varies from the selected rate, the system manifests this disparity by a visual signal and shuts itself 0E. The system is relatively fail safe, since if power fails, the intravenous feeding tube will be immediately pinched closed;

We claim:

1. In apparatus for delivering a series of drops of liquid, means defining a selected drop rate, means controlling delivery of the drops responsive to the first named means, means serving to sense each drop to be delivered and define the actual drop rate, and means serving to detect disparity between said rates and condition said means controlling delivery of the drops to arrest further delivery of drops.

2. In apparatus for delivering a series of drops of liquid, valve means operable in one condition to pass a 'drop' of the liquid to be delivered and operable in another condition to arrest the delivery of a drop or the liquid, first pulse generator means serving to provide a series of first pulses at a selected rate, second pulse generator'mean's sensing each drop of fluid to-be delivered and serving to generate a second pulse in response thereto, first and second bi-stable switch means each operatively coupled to receive and respond to receipt of said first and second pulses to change the state of bothsaid switch means and maintain the states of same in a predetermined phase condition to arrest the delivery of a drop of the liquid,

first pulse generator means serving to provide a series'of first pulses at a selected rate second pulse generator means sensing each drop of fluid to be delivered and serving to generate a second pulse in response thereto, first and second bi-stable switch means each operatively coupled to receive and respond to receipt of said first and second pulses to change the state of both said switch means and maintain the states of same in a predetermined phase relationship, said first bi-stable switch means including a pair of input connections respectively coupled to receive said first and second pulses, said second bistable switch means having a single input connection operatively coupled to receive both said first and second pulses, and means serving to sense a change in said relationship and condition said valve to the last named condition thereof.

5. An apparatus for delivering a series of drops of liquid, valve means operable in one condition to pass a drop of liquid to be delivered and operable in another condition to arrest the delivery of a drop of the liquid, first pulse generator means serving to provide a series of first pulses at a selected rate, second pulse generator means sensing each drop of liquid to be delivered and serving to generate a second pulse in response thereto, first and second bi-stable switch means each operatively coupled to re- SpOnd to receipt of said first and second pulses to change the state of both, said first and second pulse generator means being operatively coupled to direct their respective pulses to switch both said first and second switch means from one state thereof to the other in a predetermined phase relationship and means serving to sense a change in said relationship and condition said valve to the last named condition thereof.

6. In apparatus for delivering a series of drops of liquid, first pulse generator means serving to provide a series of first pulses at a selected rate, second pulse generator means sensing each drop of liquid to be delivered and serving to generate a second pulse in response thereto, first and second bi-stable switch means each operatively coupled to respond to receipt of said first and second pulses to switch the state of both said switch means to maintain the states of each in a predetermined phase relationship, means for sensing said phase relation and for detecting a change therein, and means operatively coupled to register the existence of such a change.

7. Apparatus according to claim 2 wherein said valve means is disposed to normally establish the last named condition and to establish the first named condition only so long as the phase relationship is maintained thereby requiring said phase relationship to exist in order to deliver liquid.

7 8. Apparatus according to .claim 2 further including reset means .to initially establish'said phase relationship.

9. Apparatus according to claim 2 wherein said second pulse generator means develops a'pulse of a predetermined timed duration. 7

10. 'In' 'apparatusfor delivering a series of drops of liquid, valve means operable-in one condition to passya first and second bi-stable switch means each operatively coupledto respond to receipt of said first and second pulses to change the state of both, each'said bi-stabl'e switch means serving to develop a signal representing one of the two states thereof, said signal from said first bi-stable switch means being operatively coupled to conditionsaid.

valve means to' the first named condition, said first and second pulse generator means being operatively coupled to direct their-respective pulsest'o switch both said first and second switchmeans from one state thereof to the other in a'predetermined phase relationship, means serving to sense a change in said relationship-and condition said valve to the last named condition, the last named means including disparity manifesting means to be operated in response to a change in said phase relationship and serving to condition said valve to the last named condition thereof, a first and second AND gate, each of said switch means having two output channels coupled respectively to each AND gate to transmit said signal of each switch means alternately to one or the other of the AND gates, each AND gate being operatively connected to operate said disparity manifesting means upon coincident receipt of both said signals.

including a pair of output channels to carry a given signalv 11. Apparatus according to claim It wherein said first pulse generator means is operatively coupled via said first switch means to condition said'valve to the first named conditionto deliver dropsof liquid in response to said series or" first pulses.

12. In apparatus for delivering a series. of drops of liquid, first pulse generator means serving to provide a series of first pulses at a selected rate, second pulse generator means sensing each drop of liquid to he delivered and serving to generate a second pulse in response thereto,

means serving to feed discrete drops of liquid along a path for delivery, first and second bi-stable switch means disposed to be alternately driven between two stable states by alternate receipt of said'first and second pulses to maintain an in-phase relationship, each switch means on one or. the .other dependent upon the state thereof, one of the output channels from said first switch means being coupled to condition the feeding means to feed liquid for delivery, and first and second AND gates, each coupled to both saidswitch means to normally receive saidsignal from only one of said switch means,

and means to register coincident receipt of said signals at either of said AND gates thereby indicating a change in the phase relation of said first and second switch means. 13. Apparatus according to claim 12 wherein the last named means serves to condition the feeding means to' terminate delivery of liquid.

Refere'nces Cit ed by the Examiner UNITED STATES PATENTS 2,672,581 3/54 Gorham 222 X 3,042,258 7/62 Mayes 22276 X RAPHAEL M. LUPO, Primary Examiner.

HADD S. LANE, Examiner. 

1. IN APPARATUS FOR DELIVERING A SERIES OF DROPS OF LIQUID, MEANS DEFINING A SELECTED DROP RATE, MEANS CONTROLLING DELIVERY OF THE DROPS RESPONSIVE TO THE FIRST NAMED MEANS, MEANS SERVING TO SENSE EACH DROP TO BE DELIVERED AND DEFINE THE ACTUAL DROP RATE, AND MEANS SERVING TO DETECT 